Centrally supported flameholder



FIGJ

Aug. 30, 1966 Filed April 29, 1965 T. FRASCA ETAL CENTRALLY SUPPORTEDFLAMEHOLDER 6 Sheets-Sheet l E/VMM Aug. 30, 1966 T. FRASCA ETALCENTRALLY SUPPORTED FLAMEHOLDER 6 Sheets-Sheet 2 Filed April 29, 196530, 1966 T. FRASCA ETAL 3,269,116

CENTRALLY SUPPORTED FLAMEHOLDER Filed April 29, 1965 6 Sheets-Sheet 330, 1966 T. FRASCA ETAL 3,269,116

CENTRALLY SUPPORTED FLAMEHOLDER Filed April 29, 1965 6 Sheets-Sheet 4FIG-7 Aug. 30, 1966 Filed April 29, 1965 T. FRASCA ETAL CENTRALLYSUPPORTED FLAMEHOLDER 6 Sheets-Sheet 5 0, 1966 T. FRASCA ETAL 3,269,116

GENTRALLY SUPPORTED FLAMEHOLDER Filed April 29, 1965 6 SheetsSheet 6F'IC5-|4 FICSJEJ United States Patent 3,269,116 GENERALLY SUPPUR'IEEDFLAMEHOLDER Thomas Frasca, Wethersfield, lack Rodin, Bloomfield, and

Joseph F. Loftizs, Windsor, Conn, assignors to United AircraftCorporation, East Hartford, Comm, :1 corporation of Delaware Filed Apr.29, 1965, Ser. No. 451,862 7 Claims. ((Il. 60-356) This inventionrelates to jet engine afterburner flameholders and flameholder supportand positioning apparatus.

In the past it has been conventional to support afterburner flameholders from the afterburner case or duct and this has presentedafterburner duct streaking problems which are accentuated in theturbofan engine.

It is an object of this invention to teach an afterburner flameholderwhich is supported entirely from the afterburner central support memberor cone.

It is a further object of this invention to teach an afterburnerflameholder which is one-piece construction, which includes a pluralityof trough-shaped flame stabilizing rings positioned concentrically aboutthe afterburner axis and which further includes a plurality ofsubstantially radially extending, trough-shaped flamespreader membersconnecting the flame stabilizing rings and in interior communicationtherewith so as to form a wheel-like arrangement therewith.

It is still a further object of this invention to teach an afterburnerflameholder which is supported in slip-fit arrangement from the afterend of the afterburner central support member and which is furtherpivotally supported by a plurality of aerodynamically shaped supportrods extending in pivot fashion from the central support member andpivotally connected to the flameholder so that the flameholder ispermitted to move both axially and circumferentially with respect to thecentral support cone or member and wherein the afterburner centralsupport member is supported from the engine case so that G-loads on theflameholder are transmitted to the central support member and then tothe engine case.

It is still a further object of this invention to teach an afterburnerflameholder which includes a reinforcing rib to which the afterburnerflameholder rods are pivotally attached and which includes apparatus toalign the afterburner flameholder with the fuel injection mechanism sothat motion is permitted therebetween.

Other objects and advantages will be apparent from the specification andclaims and from the accompanying drawings which illustrate an embodimentof the invention.

FIG. 1 is an exterior showing, partially broken away, of a turbofanengine showing the flameholder in its environment.

FIG. 2 is a partial cross-sectional showing through the flameholder andits support mechanism.

FIG. 3 is a partial rear view of the flameholder taken along line 3-3 ofFIG. 2.

FIG. 4 is a view taken along line 4-4 of FIG. 2.

FIG. 5 is a view taken along line 5-5 of FIG. 2.

FIG. 6 is a view taken along line 66 of FIG. 2.

FIG. 7 is a view of the afterburner flameholder support ring.

FIG. 8 is a view taken along line 8-8 of FIG. 2.

FIG. 9 is a view taken along line 9-9 of FIG. 2.

FIG. 10 is an enlarged cross-sectional view through my flameholder ring.

FIG. 11 is a graph showing the performance of my flameholder ring ascompared to a conventional, symmetric V-gutter flameholder ring.

FIG. 12 is a showing of an alternate construction of the continuoussplash plate.

FIG. 13 is a view taken along line 13-13 of FIG. l2.

FIG. 14 is a plan view, partly broken away, of the continuous splashplate construction.

FIG. 15 is a broken away showing of the continuous splash plate toillustrate fuel dispersion pattern.

Referring to FIG. 1 we see engine 10, which may be of the conventionalturbojet type but which is preferable of the turbofan or fan jet type.Engine 10 includes engine outer case 12 which is of circular crosssection and concentric about axis 14 and which includes air inletsection 16 at its forward end and variable area exhaust nozzle 18 at itsafter or rearward end. The components of engine 10 includes compressorsection 20, burner section 22, turbine section 24 and afterburnersection 26. In operation, air enters inlet section 16 and is compressedin the fan portion 28 of compressor section 20. Fan portion 28 includesa plurality of alternately positioned stationary vanes and rotatingblades. After passing through fan portion 28, a portion of thecompressed air then passes into annular bypass air passage 30, definedbetween engine case 12 and splitter duct 32, and is discharged therefrominto afterburner section 26. The remainder of the air from fan portion28 passes through high pressure compressor section 34, which comprises aplurality of alternately positioned stationary vanes and rotatingblades, for further compression therein. After leaving high pressurecompressor 34, the compressed air is heated in burner section 22 due tocombustion which takes place in combustion chambers 36, which may beeither of the conventional can or annular type, and the heated gas isthen passed through turbine section 24, where sufiicient energy isextracted therefrom to drive fan portion 28 and high pressure compressor34, and then is discharged through annular gas passage 38 formed betweensplitter duct 32 and afterburner central support member 40 and then intoafterburner 26 for eventual discharge to atmosphere through variablearea exhaust nozzle 18. Variable area exhaust nozzle 18 is ofconventional design and may be of the type more fully disclosed in US.Patent Nos. 3,032,974, 3,057,150, 3,062,003, 2,910,829, 2,974,480 or2,846,841 while engine 10 may be of the type shown in US. Patent Nos.2,929,203, 2,978,865 and 2,979,900 to which reference may be had.

A reheat process takes place in afterburner 26 and this requires theinjection of additional fuel into afterburner 26 and the establishmentof a flow stabilization zone in the afterburner so that combustion maytake place therein. Flarneholder 50 performs the flame stabilizationzone creating function.

Referring to FIGS. 2 and 3 we see flameholder 50 and its supportmechanism in greater particularity. Flameholder 50 is supported entirelyfrom afterburner central support member or cone 40 and serves to formflow stabilization zone 52 downstream thereof as the exhaust gases fromturbine 24 are passed thereover. Central support member 40, which servesto support flameholder 50, is of circular cross-section and concentricabout axis 14 and includes forward conical portion 54 and after conicalportion 56, which are axially separated to receive flameholder supportring 58 therebetween, which support ring is welded or in other fashionattached to forward cone portion 54 and after or rearward cone portion56 to cooperate therewith to form a conical structure. Central supportmember 40 is attached by bolts 60 to turbine rear bearing supporthousing 62, which is in turn supported in conventional fashion by aplurality of struts (not shown) projecting between support housing 62and engine case 12 in conventional fashion.

Support ring 58 is shown in greater particularity in FIG. 7 and includesradially extending support rib or ring 64 and a plurality of V-crosssectioned bosses 66, which include substantially rearwardly directedapertures 68 therein.

As shown in FIG. 2, rearward portion 56 of central support member 54terminates at its after end in inner diameter, cylindrical supportsurface 70.

Flameholder 50 includes sleeve member 72 which includes substantiallycylindrical, outer diameter support surface 74 at the forward endthereof which engages surface 70 of support 40 in a slip-fit, i.e.,.0O.015 inch loose. Flameholder 50 further includes a plurality oftrough or gutter-shaped, flame stabilizing rings 76, 78 and 80 which arepositioned concentrically about axis 14 and which have their open endsprojecting in a rearward or after direction. Rings 7688 are spacedaxially from one another such that the larger ring 80 is farthestforward or upstream and such that the smallest ring 76 is farthestrearward or downstream. Substantially radially directed connectors 82project from central member 40, from which they project in flared andfaired fashion as best shown in FIG. 3, and are connected to flamestabilizing rings 7680 to support these rings from support member 40.Connectors 82 are positioned circumferentially about axis 14 and arealso of trough-shaped cross section opening in a downstream direction,similar to rings 7680, and are connected to rings 76-80 so that theirinteriors are in communication, as best shown in FIG. 3. Referring toFIG. 3 we see that the interior 84 of connector 82 is in communicationwith the interiors 86, 88 and 90 of rings 76, 78 and 80 so that, oncecombustion is established in combustion support zone 52, connectors 82serve as flamespreaders between flame stabilization rings 76-80.Aerodynamic support web 92 extends along the forward or upstream edge ofconnector 82 and serves as a stiffener therefor and includes an aperture94 therein (FIG. 4) to be utilized in a fashion to be describedhereinafter.

A plurality of support rods 180 extend between flameholder 50 andcentral support member 40 to assist in supporting flameholder 50 fromcentral support member 40. Support rods 100 are pivotally attached toboth flame holder 50 and central support member 40 so that theflameholder and support member are free to move and grow thermally withrespect to one another.

The pivot connection between support rod 100 and central support member40 is best shown in FIG. 5 with further details shown in FIG. 6. It willbe noted by observing FIG. 5 that support rod 180 is actually oftwopiece construction and includes a cylindrical end 102 includingaperture 104 therethrough and having boss 106 thereover, which boss hasapertures 108 and 110 in the opposite walls thereof which align withaperture 104 of cylindrical end 102 to receive pin 112 which is held inplace by nut 114, which may be pinned or wire-locked in position throughaperture 116. Cylinder 102, it will be noted, passes through aperture 68of boss 66 of support ring 58 and includes flange 118, which abuts bossflange 120 so that the coaction of sleeve 106 and pin 112 serve toposition cylinder 102 and hence connecting rod 100 with respect to boss66 of connecting ring 58. Yoke arms 130 and 132 project from cylinder102 and include apertures 134 and 136, which align with aperture 130 insupport rod 100 to receive pin 140, which is held in position by nut 142so that support rod 100 is accordingly pivotally connected to supportring 58 and hence central support member 40.

As best shown in FIG. 4, the opposite end of support rod 100 ispivotally attached to flameholder 50. At its opposite end, support rod100 includes yoke arms 150 and 152 which have aligned apertures 154 and156 therein, which apertures align with aperture 94 of flameholdersupport web 92 to receive pivot pin 160 therethrough and pivot pin 160is held in position by nut 162.

It will accordingly be seen by viewing FIGS. 4 and 5 that connectingrods 100 are pivotally attached to the central support member 40 andflameholder 50. Accordingly, rings 7680 may thermally expand withrespect to central support member 40.

To permit reheating in afterburner 26, it is necessary to inject fuelinto the afterburner to be mixed therein with the engine exhaust gasesand to burn as a stoichiometric fuel-air mixture within the combustionstabilization zone 52 downstream of flameholder 50. Fuel is injectedthrough tubes 75 and 77, shown in FIG. 2, and passes therefrom intohollow, apertured fuel dispensing rings 79, 81 and 83 and throughapertures in the walls of these fuel dispensing rings into splash plates85, 87 and 89. Fuel rings 81, 79 and 83 are concentric about axis 14 andare of substantially thesame diameter as flameholder rings rings 76, 78and 80, respectively.

For optimum efficiency and performance, it is important that the fuelwhich is injected into afterburner 26 by the fuel rings, such as 83, becontrolled in radial dispersion and circumferential dispersion so that asymmetrical and continuous fuel-air pattern is passed axially acrosseach flameholder ring such as 80. It is essential that the radialdispersion of the fuel from the fuel rings such as 83 be controlled sothat fuel does not pass by flameholder rings 76-80 and throughafterburner 26 unburned. It is also highly desirable that the splashplate, such as 89, serve to circumferentially disperse the fuel injectedthereinto from the fuel ring 83 such that a circumferentially continuouspattern of fuel is passed axially over the flameholder ring 80.

The construction of the fuel dispensing rings and the continuous splashplates will be considered, as shown in FIG. 9, 14 and 15, to describefuel dispersing ring 83 and continuous splash plate 89.

As shown in FIGS. 9 and 14, the fuel in the fuel tube 83 passessubstantially forwardly or upstream therefrom through circumferentiallyspaced apertures 91 into the hollow interior 9 3 of circumferential,U-shaped splash plate 89 from whence the fuel is distributed uniformlyin a circumferential direction and controlled in flow in a radialdirection through circumferential apertures 95 and 97 formed top andbottom between splash plate 89 and fuel tube 83. It will be noted thatsplash plate 89 is continuous and extends circumferentially to coverseveral apertures and is broken only where required at places such asfuel tube joint 99 (FIG. 2). The axes 10 1 of apertures aresubstantially parallel to afterburner case axis 14. Continuous splash'plate 89 includes radial plate 103 spaced from and in axial alignmentwith apertures 91 and also includes axial, ringsegmented plates 105 and107, which cooperate to form channel shaped or U-shaped continuoussplash plate 8.9. Clip support members 109 attach to fuel dispensingtube 83 and to splash plate 89 so as to position flameholder 89 inspaced relation axially fonward of fuel ring 83 to establish top andbottom circumferential apertures and 97 therebetween. Clip members 109and splash plate 89 are preferably of integral construction and clipmembers 109 may be brazed or welded to tube 83.

We have found that for fuel rings of 30 to 40" diameter, fuel dispensingapertures 91 should be spaced about 2 /2 inches apart and should beabout .025 inch in diameter. The splash plate 89 should be spaced aboutA of an inch forward of ring 83. As best shown in FIG. 15, the fuelsprayed from apertures 91 sprays forwardly to strike splash plate 89 andricochet or flows rearwardly and circumferentially therefrom into thehigh velocity gas stream through afterburner 26 and is car ried axiallytherewith in a uniform circumferential pattern.

Continuous splash plate 89 serves the additional funtion of raising thenatural frequency of tube 83 and thereby improving its vibrationwithstanding qualities.

The fuel injected through rings 79, 81 and 83 is preferab-ly liquid,such as kerosene or other similar liquid hydrocarbon compounds.

Test results and motion pictures show that such a splash plateconstruction provides fuel of uniform circumferential distribution andof controlled radial distribution to an afterburner flame stabilizationring, such as 80, downstream thereof. The fuel so injected will beburned in flow stabilization zone 52 downstream of the flameholder 50.

An alternate embodiment of the continuous splash plate is shown in FIGS.12 and 13. Referring to these two figures we see hollow fuel dispensingtube 83 which has forwardly oriented and circumferentially spaced fueldispersing apertures 91' therein. Continuous splash plate 8 9' comprisessupport clip members such as 300 which include radially outer clip legssuch as 302 and radially inner clip legs such as 304 attached by eithera clipping or pinching action or by brazing to tube 83' in radialalignment with each aperture 91 and defining an axially forwardlydirected passage 306 forward of each aperture 91'. Clip legs 302 and 304attached to U-shaped bracket 308, which is of U-shaped cross-sectionopening toward tube 83 and axially spaced therefrom and in axialalignment with apertures 91' and extending circumferentially thereof.Continuous channel member 310 attaches to U-shaped clips 300 and bridgesthe circumferential gap therebetween to cooperate therewith in defininga continuous, circumferential channel aligned with and bridging thecircumferential gap between fuel dispensing apertures 91'. U-channelmember 310 is arcuate in shape to follow the circumferential curvatureof tube 83' and is of U-shaped cross-section opening toward tube 83.

Flarneholder 50 has a plurality of circumiferentially spaced ball endedpins 101 extending forwardly therefrom and received into sleeved bosses103, which projects rearwardly from fuel ring 83. Support pin 105pivot-ally connects pin 101 to flameholder 50 so that pin 101 and sleeve103 serve to keep flameholder ring 80 and fuel spray tube 8 3 in axialalignment, while permitting relative motion therebetween.

While flameholder 50 serves to establish combustion stabilization zone52 downstream thereof to permit the reheating of the exhaust gases beingdischarged through annular passage 38, combustion or reheating must alsotake place in afterburner 26 downstream of the bypass annular passage 30defined between engine or afterburner case or duct 12 and splitter duct32. Flameholder 170 (see FIG. 2), which is of trough-shapedcross-section and in the form of a ring concentric about axis 14 ispositioned downstream of annular bypass gas passage 30 by a plurality ofsupport rods 172, which are pivotally attached to flameholder ring 174at pivot points 176 and which are also attached to engine or afterburnerduct 12 or afterburner liner 177 at pivot points 178 through bossarrangement 180. Bypass air flameholder ring 170 has cold air frompassage 30 passed thereover and serves to form flow stabilization zone182 downstream thereof in which the fuel which is injected through fuelinject-ion means 184 may be ignited and burned. It is a very diflicultproblem to ignite and sustain combustion in a cold gas stream such asthe one in which flameholder 170 .is located and it is accordingly animportant teaching of this invention that flameholder 50 be made as bestshown in FIGS. 2 and so that it consists of inner wall 186, which issubstantially cylindrical and concentric about axis 14, and outer wall188 which diverges in a downstream direction with respect to axis 14such that it projects toward cold air flameholder 170 to define anincluded angle of about 30 with inner wall 186 and is smoothly joined toinner wall at leading edge 312. Further, a circumferentially extendingaerodynamic trip in the form of circum'ferentially extending andinwardly projecting lip or flame 190 (FIGS. 2, 3 and 10) is attached tothe after or downstream end of cylindrical wall 186 of flameholder ring80 and serves to cause the air flowing therearound to recirculate, asshown in FIG. 10,

.toward the interior 314 of flameholder ring 80. Similar recirculationis caused by the air flowing over outer wall 188 as shown in FIG. 10.The specific shape of .ring 80 shown in FIG. 10 establishes a hotgas-cold gas interface or flamefront to project along line 111 and outinto the cold air stream downstream of passage 30 and into combustionzone 182 formed downstream of flameholder 170. This flamefront orinterface 111 intercepts cold air-hot gas inter-face 11-3 defined bysplitter duct 132 so as to force hot air or flame into combustion zone182.

By referring to FIG. 11 we can see the improvement in performanceobtained by the use of flameholder ring shaped as shown in FIG. 10 asopposed to a conventional and symmetrical trough-shaped ring of the typeillustrated for flameholder rings 76 and 78. Curve A represents theperformance curve for the conventional ring such as 76 or 78 when usedin the flameholder 80 position, whereas curve B represents theperformance curve for flameholder 80 of the type shown in FIG. 10. Itwill be noted that for any given afterburner inlet pressure level (i.e.altitude), the stable operational range from lean to rich fuel airratios is vastly greater for the flameholder ring shaped as shown inFIG. 10 (curve B) as compared to the conventional ring (curve A). Itshould also be noted that the capability for operation to higheraltitudes, as represented by reduction in afterburner inlet pressure, issignificantly improved for the flameholder ring shown in FIG. 10 (curveB) as compared to the conventional ring (curve A).

It is also an important teaching of this invention that a plurality ofcircumferentially positioned and troughshaped flamespreaders 200 (FIGS.2 and 3) project outwardly from flame stabilizing ring 80 and projectdownstream therefrom toward flameholder ring in such a fashion that theyincrease in cross-sectional area in a downstream and radial outwarddirection to form a venturi as shown in FIG. 3. To be more specific, theinner end 202 of each flamespreader 200 is of intermediatecross-sectional area and tapers down to throat 203, which is of minimumcross-sectional area, then increases in cross-sectional area so thatouter end 204 thereof is of maximum cross-sectional area. It will benoted that the after or outer end 204 of flamespreader 200 issubstantially in radial alignment with cold stream flameholder 170 andserves to carry flame from flame stabilization ring 80 to flamestabilization ring 174 of flameholder 170 both to provide ignition offlameholder 170 in the case of a zoned afterburner and to provide addedassistance for proper combustion of flameholder 170 located in the coldbypass airstream by providing added heat in the recirculation zone ofthis flameholder. By providing a large crosssectional area inflamespreader 200 at its outer end 204 we are establishing a lowpressure region at 204 with respect to the pressure at the inner end 202of the flameholder. This pressure dilferential causes a heat or flamepumping action from flameholder ring 80 to flameholder ring 170 in thecold air stream.

In afterburner operation, fuel is injected through fuel line 77 (FIG. 2)into flameholder ring 83 and passes therefrom against continuous splashplate 89 and is then carried by the engine exhaust gases in passage 38symmetrically around flame stabilizing ring 80 to be ignited downstreamthereof and in the interior thereof by a conventional hot-stream ignitershown as element 320 in FIG. 1 and of the type taught and fullydescribed in US Patent No. 2,913,875 to which reference is hereby made.Fuel from fuel rings 79, 81 and 184 is then caused to pass aroundflameholder rings 78, 76 and 170 respectively. The flame established inthe interior of flame stabilization ring 80 will flow through theinterior of flamespreader connectors 82 and 200 to establish combustionin and downstream of flame support rings 76 and 78 and in and downstreamof cold path flameholder 170.

It is to be understood that the invention is not limited to the specificembodiment herein illusrated and described but may be used in other wayswithout departure from its spirit as defined by the following claims.

7 Iclaim: 1. A flarneholder assembly having an axis, a central supportmember concentric about said axis and having a substantially cylindricalsupport surface at its after end and support bosses forward thereof, aflarneholder having a plurality of rings of gutter-shaped cross-sectionpositioned concentrically about said axis and a plurality of radiallyextending connectors of gutter-shaped crosssection extending betweensaid rings and connected thereto and in interior communication therewithto support said rings and including an inner support sleeve attached tosaid connectors and having a substantially cylindrical support surfacein slip-fit engagement with said substantially cylindrical supportsurface of said central support member, and support rods pivotallyattached to said flarneholder and to said support bosses so that saidflameholder is supported by said central support member.

2. A flarneholder assembly having an axis, a central support member ofcircular cross-section and concentric about said axis and having asubstantially cylindrical support surface at its after end and a supportring forward thereof and concentric about said axis and having aplurality of circumferentially spaced bosses positioned therein, aone-piece flameh-older having a plurality of rings of gutter-shapedcross-section positioned concentrically about said axis and a pluralityof radially extending connectors of gutter-shaped cross-sectionextending between said rings and connected thereto and in interiorcommunication therewith to support said rings and including an innersupport sleeve attached to said connectors and having a substantiallycylindrical support surface in slipfit engagement with saidsubstantially cylindrical support surface of said central supportmember, and support rods pivotally attached to said flarneholder and tosaid support bosses so that said flarneholder is supported by saidcentral support member.

3. A flarneholder assembly having an axis, a central support member ofcircular cross-section and concentric about said axis and having asubstantially cylindrical support surface at its after end and a supportring forward thereof and concentric about said axis and said supportring having a plurality of circumferentially spaced bosses positionedtherein, a onepiece flarneholder having a plurality of flame supportingrings of guttershaped cross-section positioned concentrically about saidaxis and a plurality of radially extending flame spreading connectors ofgutter-shaped cross-section extending between said rings and connectedthereto and in interior communication therewith to support said ringsand including an inner support sleeve attached to said connectors andhaving a substantially cylindrical support surface in slip-fitengagement with said substantially cylindrical support surface of saidcentral support member, a reinforcing web extending along each of saidconnectors, and support rods pivotally attached to said reinforcing websand to said support bosses so that said flarneholder is supported bysaid central support member.

4. A flame-holder assembly having an axis, a central support member ofcircular cross-section and concentric about said axis and having asubstantially cylindrical outer diameter support surface at its afterend and a support ring forward thereof and concentric about said axisand said support ring having a plurality of circumferentially spacedbosses positioned therein, a one-piece flarneholder having a pluralityof flame supporting rings of guttershaped cross-section positionedconcentrically about said axis and a plurality of radially extendingflame spreading interconnectors of gutter-shaped cross-section extendingbetween said rings and connected thereto and in interior communicationtherewith to support said rings and includ ing an inner support sleeveattached to said interconnectors and having a substantially cylindricalinner diameter support surface in slip-fit engagement with saidsubstantially cylindrical support surface of said central supportmember, a reinforcing web extending along each of said interconnectors,and support rods of airfoil cross-section pivotally attached to saidreinforcing web and to said support bosses so that said flarneholder issupported by said central support member.

5. An afterburner including a flow confining duct having an axis, acentral support member of circular crosssection and concentric aboutsaid axis and having a substantially cylindrical support surface at itsafter end and support bosses forward thereof, said duct enveloping saidcentral support member to define an annular gas passage therebetween, aflarneholder located in said annular gas passage and having a pluralityof rings of gutter-shaped cross-section positioned concentrically aboutsaid axis and a plurality of radially extending connectors ofguttersh'a-ped cross-section extending between said rings and connectedthereto and in interior communication therewith to support said ringsand including an inner support sleeve attached to said connectors andhaving a substantially cylindrical support surface in slip-fitengagement with said substantially cylindrical support surface of saidcentral support member, and support rods pivotally attached to saidflarneholder and to said support bosses so that said flarneholder issupported by said central support member.

6. An afterburner including a duct of circular crosssection concentricabout an axis and having a forward and rearward end, a conically shapedcentral support member of circular cross-section and concentric aboutsaid axis and enveloped within said duct to form an annular gas passagetherebetween and including a cylindrical inner diameter support surfaceat its after end and a support ring forward thereof, said centralsupport member including axially spaced forward and rearward wallmembers, said support ring including a first surface joining saidaxially spaced central support wall members and having a radiallydirected rein-forcing ring projecting inwardly therefrom and furtherhaving a plurality of circumferentially positioned bosses thereabout andwhich bosses are of substantially V-shaped cross-section and include asubstantially rearwardly directed aperture in one wall thereof, aone-piece fiameholder positioned concentrically about said axis andincluding a sleeve member having a substantially cylindrical outerdiameter support surface engaging said support surface of said centralsupport member in slip-fit relation and further including a plurality oftrough-shaped flame supporting rings positioned concentrically aboutsaid axis with the troughs thereof opening in a rearward direction andwith the rings spaced axially so that the largest ring is farthestforward and the smallest ring is farthest rearward and further includinga plurality of trough-shaped, circumferentially spaced flame spreadingconnectors extending in a substantially radial direction between saidflame supporting rings so that said connectors cooperate with said ringsto form a wheel-like arrangement and being connected to said rings andto said support sleeve to support said rings from said support sleeve, areinforcing Web extending forwardly along the forward edge of eachconnector and including an aperture therethrough, a plurality of supportrods pivotally connected to said flarneholder and said support ring sothat said flameho-lder is supported from said central support member,each of said support rods including a cylindrical end which projectsthrough said aperture in said support ring boss and which has anaperture extending therethrough, a collar sleeved over said cylindricalend of said support rod and having apertures in the opposite wallsthereof aligned with the aperture in said support rod cylindrical end, apin member extending through said apertures of said collar and saidsupport rod cylindrical end to connect said support rod to said supportring boss, each of said support rods also being yoke shaped at itsopposite end and having aligned apertures in the opposite arms thereofwhich are aligned with said apertures in said connector reinforcing web,pin means pivotally connecting said support rod yoke end to saidconnector rein- 9 forcing web, each of said connectors also including apivot joint between said cylindrical end and said yoke end.

7. Apparatus according to claim 6 and including means to inject fuelinto said annular gas passage forward of said fiameholder, and means toalign said fuel injection 5 means and said flameholder.

References Cited by the Examiner UNITED STATES PATENTS 2,564,042 8/1951Walker 60-39.32 X 10 Taylor 60-356 Carr 60-39.32 X

Karcher 60-39.32 X

Hopper 6039.72

Meyer 60-3946 MARK NEWMAN, Primary Examiner.

RALPH D. BLAKESLEE, Assistant Examiner.

1. AW FLAMEHOLDER ASSEMBLY HAVING AN AXIS, A CENTRAL SUPPORT MEMBERCONCENTRIC ABOUT SAID AXIS AND HAVING A SUBSTANTIALLY CYLINDRICALSUPPORT SURFACE AT ITS AFTER END AND SUPPORT BOSSES FORWARD THEREOF, AFLAMEHOLDER HAVING A PLURALITY OF RINGS OF GUTTER-SHAPED CROSS-SECTIONPOSITIONED CONCENTRICALLY ABOUT SAID AXIS AND A PLURALITY OF RADIALLYEXTENDING CONNECTORS OF GUTTER-SHAPED CROSSSECTION EXTENDING BETWEENSAID RINGS AND CONNECTED THERETO AND IN INTERIOR COMMUNICATION THEREWITHTO SUPPORT SAID RINGS AND INCLUDING AN INNER SUPPORT SLEEVE ATTACHED TOSAID CONNECTORS AND HAVING A SUBSTANTIALLY CYLINDRICAL SUPPORT SURFACEIN SLIP-FIT ENGAGEMENT WITH SID SUBSTANTIALLY CYLINDRICAL SUPPORTSURFACE OF SAID CENTRAL SUPPORT MEMBER, AND SUPPORT RODS PIVOTALLYATTACHED TO SAID FLAMEHOLDER AND TO SAID SUPPORT BOSSES SO THAT SAIDFLAMEHOLDER IS SUPPORTED BY SAID CENTRAL SUPPORT MEMBER.
 5. ANAFTERBURNER INCLUDING A FLOW CONFINING DUCT HAVING AWN AXIS, A CENTRALSUPPORT MEMBER OF CIRCULAR CROSSSECTION AND CONCENTRIC SUPPORT SURFACEAT ITS AFTER END AND STANTIALLY CYLINDRICAL SUPPORT SURFACE AT ITS AFTEREND AND SUPPORT BOSSES FORWARD THEREOF, SAID DUCT ENVELOPING SAIDCENTRAL SUPPORT MEMBER TO DEFINE AN ANNULAR GAS PASSAGE THEREBETWEEN, AFLAMEHOLDER LOCATED IN SAID ANNULAR GAS PASSAGE AND HAVING A PLURALITYOF RINGS OF GUTTER-SHAPED CROSS-SECTION POSITIONED CONCENTRICALLY ABOUTSAID AXIS AND A PLURALITY OF RADIALLY EXTENDING CONNECTORS OFGUTTERSHAPED CROSS-SECTION EXTENDING BETWEEN SAID RINGS AND CONNECTEDTHERETO AND IN INTERIOR COMMUNICATION THEREWITH TO SUPPORT SAID RINGSAND INCLUDING AN INNER SUPPORT SLEEVE ATTACHED TO SAID CONNECTORS ANDHAVING A SUBSTANTIALLY CYLINDRICAL SUPPORT SURFACE IN SLIP-FITENGAGEMENT WITH SAID SUBSTANTIALLY CYLINDRICAL SUPPORT SURFACE OF SAIDCENTRAL SUPPORT MEMBER, AND SUPPORT RODS PIVOTALLY ATTACHED TO SAIDFLAMEHOLDER AND TO SAID SUPPORT BOSSES SO THAT SAID FLAMEHOLDER ISSUPPORTED BY SAID CENTRAL SUPPORT MEMBER.